1. Field of the Invention
The present invention relates to a chair backrest. In particular, the present invention relates to a chair-backrest with improved stability, improved sitting comfort, and improved safety.
2. Description of the Related Art
FIGS. 5 and 6 of the drawings illustrate a conventional chair including a backrest 1xe2x80x2, a seat 2xe2x80x2, a chassis 3xe2x80x2, a leg assembly 4xe2x80x2, and a connecting plate 5xe2x80x2. 2he backrest 1xe2x80x2 includes an engaging portion 11xe2x80x2 with fixing holes 12xe2x80x2 on a lower central portion thereof for connection with the connecting plate 5xe2x80x2. The chassis 3xe2x80x2 is fixed to a central portion of an underside of the scat 2xe2x80x2 and includes a lower end for connection with the leg assembly 4xe2x80x2 and an engaging portion 31xe2x80x2 with fixing holes 32xe2x80x2 for connection with the connecting plate 5xe2x80x2. The connecting plate 5xe2x80x2 is a substantially L-shaped plate including two plate sections having fixing holes 51xe2x80x2 and 52xe2x80x2 through which screws are extended for connecting the backrest 1xe2x80x2 and the seat 2xe2x80x2 in a perpendicular manner.
The backrest 1xe2x80x2 is supported by the connecting plate 5xe2x80x2 when the user is lying down. However, the supporting point provided by the connecting plate 5xe2x80x2 is only at the lower central portion of the backrest 1xe2x80x2 such that the forces exerted on the two sides of the backrest 1xe2x80x2 are not uniform when center of gravity of the user""s back shifts as a result of movement of the user. As a result, the connecting plate 5xe2x80x2 could not provide a stable support when the user""s back is not lying flat in the backrest 1xe2x80x2.
An object of the present invention is to provide a chair backrest with improved stability, improved sitting comfort, and improved safety.
A chair in accordance with the present invention includes a seat, a chassis fixed to an underside of the scat, a leg assembly attached to an underside of the chassis, a backrest, and a support frame. A plurality of engaging posts are formed on a peripheral portion of a rear side of the backrest, each engaging post having a groove, each engaging post further including a transverse fixing hole. The support frame extends along the peripheral portion of the rear side of the backrest A connecting beam includes a first end fixed to a lower portion of the support frame and a second end fixed to the chassis.
A plurality of connecting blocks are provided fixing the support frame to the rear side of the backrest. Each connecting block includes a sleeve portion through which the support frame extends. Each connecting block further includes an insertion portion engaged in the groove of the respective engaging post. The sleeve portion of each connecting block includes a slit allowing expansion of the sleeve portion when the support frame is extending through said connecting block. A fastener is extended through the transverse fixing hole in the respective engaging post into the insertion portion of the respective connecting block.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.